Method of evaporating liquids



June 21, 1932. F. x. GovERs I uTHoD oF EVAPORATING LIQUIDs Filed Nov. 5,1928 4 Sheets-Sheet 1 IllIl j @www1 I l I I l I I IJ I I l I I l IL June2l, 1932. F. x.A GovERs 1,864,349

METHOD 0F EVAPORATING LIQUIDs Filed Nov. 5, 1928 4 Sheets-Sheet 2Conden- Sae ol/ June2l, 1932. F. x. GovERs I 1,864,349

' METHOD OF EVAPORATING LIQUIDS Filed Nov. l5:3, 1928 4 Sheets-SheetI 3@ya il (xg) v J0 5 '-Ey-g June 21, 1932. 4F, x, GQVERS 1,864,349

METHOD OF EVAPORATINGJIQUIDS Filed Nov. 5, 1928 4 Sheets-Sheet 4- memeJune 21, 1932 UNITED` STATES FRANCIS X. GOVEBS, OF LAW'BENCEVILLE,

PATENT OFFICE N ILLINOIS, ASSIGN'OIR. T0 INDIAN REFINING COMPANY, OFLAWRENCEVIILE, ILLINOIS, A CORPORATION F MAINE METHOD OF EVAPORATINGLIQUIDE .Application led November 1 fractional overhead cuts in themanufacture of lubricating oils has long been recognized. The markedadvantages of making such a fractionation under low absolute pressurehave been pointed out, as well as the fact that it is possible to obtainby this means overhead distillates with as great a viscosityy asdesired, and within extremely narrow boiling point ranges. Fractionalcuts of definite chemical composition can be produced in this manner.

In the commercial application of this principle, however, diiiiculty hasbeen experienced because of the extreme readiness with which petroleumoils and their products break down under elevated temperature conditionswith the resulting production of carbon and undesirable vaporous andgaseous decomposition products.

It must be kept in mind that the indicated temperature of anyconsiderable mass of oil in process of distillation is only a meantemperature indication, and partsof the mass vmay have been heated farabove that of the indicated temperature. Thus these well knownladvantages of distilling petroleum products under conditions of lowabsolute pressure and a comparatively low and safe temperature are lostbecause parts of the mass are heated above the temperatureI at which thedecompose. This tendency of arts of t e mass being heated beyond themdicated temperature is accentuated in the case of petroleum oilsbecause of their relatively high viscosity and sluggish heat con'-ductivity.

Further, in the ordinary type of cylindrical stills, as proposed fordistillation undery low absolute pressure, where a considerable depth'of oil is being heated, a considerable 5, 1928. Serial No. 817,297.

portion of the mass is under a pressure much greater than that desiredor recommended,

and many of the claimed advantages are lost v because of the fact thatall portions of the oil are not under like conditions either of.

pressure or of temperature.

It is desirable in all types of lubricating oils that the flash point beas high as possible for any given viscosity oil and this desirablequality is lost in part whenever the oils under treatment are subjectedin whole or in part to too high temperature conditions.

According to my invention these diicull ties are largely obviated byconducting. the distillation under a very low absolute pres sure,advantageously about mm. absolute in a still the oil being heated by anindirectly heated heating element which can be maintained at the desiredtemperature, and circulating the oil by a forcevpump in rapid flow overthe heatin element.

By controlling t e temperature of the heating element 1n relation tothat of the oil flowing over it and causing the oil to flow at asuiiciently rapid rate, any desired tempera- 4ture difference betweenthe oil and the he'ating surface can be maintained, while at the sametime a high rate of heat transfer is obtained.

There results a minimum of change in the oil under treatment with theretention of all the desired qualities in both its liquid or solidhydrocarbon components, while a rapid rate of distillation is obtainedwith resulting increase in production.

My invention is not restricted to the use of any particular apparatus,but one form which has in practice been found to be highly successful isshown in the accompanying drawings.

Referring to the drawings: Fig. 1 is an elevation of the apparatus; Fig.2 is a. sectional detail of the oil heater element;

Fig. 3 is a sectional elevation of a boiler in the'apparatus consists ofan evaporator Gsaving an outlet 8 connected by flange 9 to the inlet 10to the condenser 11. Condenser 11 is connected to receiver 12 by meansof a barometricdischarge pipe 13. The condenser 11 is further providewith a water inlet 14 and water -outlet 15, and is connected to a I jetejector 16 by means of (pipe 17.

The heating element 5 hown in detail in Fig. 2) and the evaporator 6are. connected by a. circulating system comprisin downtake pipe 19circulating pump 20 an lip-take pipe 21. The heatin element 5 (see ig.2) coin rises an outer s ell 22, provided with headers 23 and 24 intowhich are expanded tubes 25. The upper header 23 is secured to the shell22 which has, at its lower end an enlarged portion 22 within which is apacking chamber. Extending upwardly from the header 24 is a cylindricalshell 24',V between which andf 22 Y acking material, advanta eouslyasbestos ber, is located, which is hel in place by a gland member 60.This arrangement allows for expansion of the tubes without undue strain.At its upper portion the shell 22 is surrounded by a Jacket 26, theintermediate space being advantageously filled with heat insulatingmaterial 27. This construction need not be further s ecificall describedas it will be apparent rom the rawings. The heating element isadvantageously heated by hot vapor entering through the neck from thepipe 31,` provided with valve 56, which is connected to the boiler 32.The heatin vapor passes upwardly around through t e space between shell22 and the shell 33 which surrounds the tubes 25, throu h which the oilpasses, and the vapor then ows downwardly in contact with these tubes.The vapor is thereby condensed and collects in the bottom of the chamberabove the header 24, and flows outwardly through the neck 34 which isconnected to'the pipe 35 leading to a pump 36 by which it is returnedthrough pipe 57 aving check valve 58 to pump 39 and thence through pipe37 leadn into a chamber 37 at the bottom of the boi er 32.

The boiler 32 is supplied with a high boiling point liquid, such asdiphenyl, delivered by sup ly pump (not shown) through pipe 38 lea ingto a circulating pump 39 from which it is delivered by pipe 37 intochamber 37 and thence into a series of tubes 41 mounted between headers42, 43. The bank of tubes 41 is mounted within a brickwork stack 44which may be heated in any suitable manner, as by hot gases deliveredinto the lower portion of the hea-ting chamber 45' through a connection46 (shown in dotted line) leading to any suitable heat supply. Theliquid passing through the pipes is delivered against a spreader 62 intoa vapor chamber 47 having a safety valve 61, from which chamber thevapors are delivered through pipe 31 and pressure regulating valves 5656 to the vapor inlet 30 of the heating e ement 5.

The unvaporized liquid passesfrom the chamber 47 through the pipe 48 tothe pump 39 and is circulated through the heated tubes. These pipes 48,31 and 35 are provided with suitable ends to provide for expansion andcontraction.

From the heating chamber 45 the hot gases ma be delivered into a stack50.

s a high boilin liquid, I may advantageously use melte di henyl, whichmelts at about 158 F. and boils at about 485 F., and at a pressure ofapproximately 110 pounds has a temperature -of about 750 F.

I have found that diphenyl posseses certain advanta es not ossessed byother heating media. have een enabled to operate the same as aheat-exchanging medium for periods of many months and at continuouslmaintained temperatures of over 700 without the formation off/tars,decomposition products and gases, and substantially without change inthe chemical urit of the diphenyl. Such temperatures ave en in the rangewhere other organic heating media undergo considerable and progressivedeterioration with the formation of tars which will carbonize on'theheating surfaces. On the other hand, diphenyl has been found to re-jmain of such purity as to enable substantially complete vaporization ofthe same at all times. l

Furthermore, .diphenyl vapors when applied to the heat exchan e surfacescondense and full wet these sur aces so that an ellicient an completecontact is maintained at all times between the heat exchange surfacesand the fresh incoming diphenyl vapors. By reason of the efficient andready transfer of heat from the condensing diphenyl vapors a very lowheat differential between the vapors and the fluids being heated can bemaintained.

This is of great importance in the heating of organic fluids generallyand is of particular importance in the heating of mineral oilspreparatory to distillation for the reduction of high grade lubricatingoils. t is there especially important to avoid all traces of cracking bylocal overheating, and it is possible to accomplish this by the use ofthediphenyl heating system by reason of the ellicient heat transfer atlow temperature dif-I ferential.

By means of the system shown, the tubes inthe heating element 5 areexternally heated by the hot diphenyl vapor and can therefore readilymaintained at any desired temperature.

The oil is continuously forced upwardly by the pump 20 through theheated tubes 25 and the mixed liquids and vapors are dischar against thespreader 51 in order to permit the vlos.

izo

se aration of the oil vapors from the liquid oi which flows downwardlythrough the pipe 19 to the pump 20.

The temperature of the vapor delivered through pipe 31 is controlled byvarying the pressure under which the high-boiling point liquid isvaporized. The temperature of the tubes through which the-oil iscirculated can thus` be accurately controlled. The rate at which the oilis heated in its passage through the heated tubes may be controlled byvarying the speed of the circulating pump 20.

There can thus readily be maintamed any desired tempera-ture differencebetween the heated surfaces and the owing oil in contact therewith,thereby enabling the gradual, uniform heating of the body of oil to thedesired distillation temperature without any danger of overheatingportions thereof, and cuts may be taken oil' within as narrow ranGes oftemperature as considerations may dictate.

All pipes conveyinghot liquids or vapors are heavily insulated to avoidloss of heat, and all' pipes containing diphenyl are provided with meansfor liquefaction or for maintaining the diphenyl in liquid state.

The pipes 19 and 2O are provided with slip joints 52 and 53 to providefor expansion and contraction. .v

The heating element is also provided, as above described, with meansincluding the member for permitting movement due to expansion andcontraction because of varying temperature conditions of the shell 24',con nected to and forming part of the tubesheet 24, which is in turnconnected to pipe 21.

Pipe 21 is free to move in the slip joint 53. This arrangement permitsthe up and down movement of the lower tube sheet, and thus avoids unduestrains.

The system is provided at all necessary p oints with heat and pressureindicating devices.

One form of condenser which has been found in practice to beadvantageous is shown in Figs. 4 and 5.

.The condenser 11 as a whole is supported on a neck 10, by a flangedconnection 9 to the outlet 8 of evaporator 6. Secured to the inner wallof the neck 10, as by electric We1ding is an upwardly extending vaporpipe 70, around which is a casing 71, enclosing heat insulating material72.

Extending across `the shell 73, and above the outlet of vapor pipe 70,is a tube sheet 7 4, from which depend tubes 75, into the space betweenthe vapor pipe and the shell 73. These tubes are closed at their bottomsby caps 76, secured to a grid 77, which is supported by angle irons 98carrled by shell 73.

A second tube sheet 78 extends across the shell above the tube sheet 74,and from this `chamber 82 formed between this upper sheet 78, and thetop 80 of the condenser, extends a pipe 14 for cooling liquid, such. aswater. rom this chamber 82 the coollng liquid Hows down through pifpes79 and up through pipes 75, discharging rom the upper ends of pi s 79intoA the chamber between' the two tubi; sheets, from 'which the liquidis discharged through pipes 15, 15. The tube sheets are braced by aperforated diaphragm 85. At its lower portion, the condenser is rovidedwith a shell 86, secured hermeticaly, as by weldin to shell 73. At theupper portion of the s ell is a pipe connection 17, to which may beconnected a vacuum producing apparatus. Covered manholes 88, 88, areprovided in the shell 86 to afford means of access. One or more exitopenings to which are connected pipes 13, 13', serve for discharge ofthe condensed liquid. Advantageously there is provided a hood 90extending between the bottom of shell 86 and casing 71. In operation,the hot vapors rising through the heat insulated tube are dischargedagainst the surroundin cooled tubes and the condensed liquid co lects inthe bottom portion of the structure in the chamber 91.

As shown, this self-contained condenser is mounted directly upon and inopen communication with the vapor space of the still 6, and is thus freeto expand and contract in accordance with variations in temperature.

It will be evident that by the use of this apparatus the oil to bedistilled can be gradually heated to the required temperature withoutlany possibility of overheating such as is liable to occur infire-heated pipe stills or cylinder stills, sincethe temperaturedifference between the vheated surface and the oil contacting therewithcan be controlled as desired or required.

lVhile my invention has been described as applied to the manufacture oflubricating oils from petroleum hydrocarbons, the method'is equallyapplicable to the evaporation, as for concentration purposes, of otherliquids, such vas caustic soda lyes, etc., from which it may be .desiredto evaporate a liquid, while maintaining the residual portion at a. hightemperature.

I claim:

1. Process of vaporizing petroleum oils in vacuo which consists insupplying to the oil the heat'required for distillation thereof by rapidcirculation of the oil in heat transfer relation with indirectly heatedsurfaces maintained at controlled temperatures above that of the oilcontacting therewith by means of a hot vapor of diphenyl.

2. In the process of vaporizing liquid inl vacuo the steps which consistin supplying to such liquid the heat required for evaporation by rapidcirculation of the liquid in heat transfer relation with indirectlyheated surfaces maintained at controlled temperatures above that of theliquid contacting therewith by means of the hot vapor of diphenyl.

3. In the heating of petroleum oil the step of imparting heat to suchoil by means of diphenyl in t ermal but out of physical contact with theoil and heated to a temperature in excess of the temperature ofthe oil.4. In the heating of petroleum oil the step of impartin heat to the oilby means of the vapor of dip enyl in thermal but out of physical contactwith the oil but at a tem rature in excess of the temperature of the011.

5. The method of heating petroleum oil which comprises boiling a body ofdiphenyl in a heat transfer system,1eadin the vapors into indirect heatexchange relatlonship with the oil to be heated, eiecting condensationof the diphenyl and absorption of its latent heat of vaporization by theoil to be heated, and returnm the diphenyl condensate to the body of dipenyl maintained substantially free from decomposition roducts.

6. In the heating of uid materials the step of im'partn heat to suchfluid material b means of dip enyl in thermal but out of physicalcontact with` the fluid material and heated to a temperature in excessof the temperature' of the fluid material.

7 In the heating of fluid materials the step of imparting heat to suchHuid material by means of the vapor of diphenyl in thermal but out ofphysical contact with the fluid material, and at a temperature in excessof the temperature of the fluid material.

8. The method of heating fluids which comprises boiling a bod ofdiphenyl in a heat transfer system, leading the vapors into ins directheat exchange relationship with the Huid to be heated, effectingcondensation of the diphenyl and absorption of its latent heat ofvaporization by the fluid to be heated, and

returning the diphenyl condensate to the body of diphenyl maintainedsubstantially free from decomposition products.

In testimony whereof, I aiiix nygiature.

FRANCIS X.

